…or does it? 25 years after it left the earth, and 13.5 billion kilometres away from the sun (or 90 times farther away from the sun than the Earth), competing papers in this weeks Nature debate whether Voyager 1 has left the solar system and entered interstellar space.

“Voyager 1 was launched 26 years ago and has nearly reached – or has already penetrated – the edge of the bubble surrounding the solar system.

The bubble is formed when highly charged particles from the sun, called the solar wind, collide with particles emanating from other stars in the galaxy.

The edge of the bubble, called the heliopause, is an ever-shifting boundary and it’s unclear whether Voyager 1 has passed through it.Scientists theorize that a barrier, called a termination shock, exists where the hot solar wind hits the cold, thin gas of interstellar space.

As particles of solar wind pile up on the barrier, they get hotter and skip back and forth across the boundary. ” —CBC

Scientists race against the exhaustion of its onboard power source in hopes it will find something interesting in the endless expanse of interstellar space it now enters on ithe final (but interminable) leg of its voyage.